Currently, SE Asia is the global marine centre of diversity. High diversity is concentrated in and around reefs. A large variety of organisms, including corals and fish, but also molluscs, crustaceans and echinoderms contribute to this high diversity. In order to understand the timing and the context of the origin of the modern biodiversity hotspot, the fossil record needs to be documented. However, reef facies often suffer strong diagenesis, compromising the fossil record of reef and reef-associated organisms. Here we present an assessment of a well-preserved Late Miocene mollusc fauna from Bontang (East Kalimantan, Indonesia). The fauna is found in association with branching corals, dominated by Dictyaraea. The mollusc fauna is dominated by predatory and browsing carnivorous snails and includes reefal indicators such as the gastropod Coralliophyla and the bivalve Tridacna. The new Bontang fauna gives a glimpse of the diversity and ecological composition of a Late Miocene mollusc fauna from a so-called coral-carpet environment.